An organic electroluminescent device is actively researched and developed because light emission with high luminance is obtained by low-voltage drive. The organic electroluminescent device has an organic layer between a pair of electrodes and utilizes energy of an exciton as produced upon recombination of an electron injected from a cathode and a hole injected from an anode in the organic layer for light emission.
In recent years, realization of high efficiency of the device is advancing by using a phosphorescent material. While there have been disclosed inventions regarding a phosphorescence emitting device using, as the phosphorescent material, an iridium complex, a platinum complex or the like, any device capable of making both high efficiency and high durability compatible with each other has not been developed yet.
Also, though there have been made attempts to use a stable metal complex as a host material (see, for example, U.S. Pat. No. 6,303,238), light emission efficiency and durability thereof are not sufficient yet. It is the present situation that the development of a device exhibiting higher light emitting luminance and light emission efficiency and having excellent durability is eagerly demanded.